They may have stopped supporting that app in favor of the fandom app. Or at least slowed down support for it.

^^^ I know that, but the specific app for warframe says that it is not available to my region or country (I live in Texas)

Its within that fandom app, you just need to follow it, so an individual warframe app is unnecessary. Mine disappeared a few months ago

The FANDOM should work. I know people who live in Texas and use FANDOM app.

I got some problem for mine